Breech mechanism



May 3,1927. 1,626,651

- P. D. VAN ESSEN ET AL BRBECH MECHANI SM Filed July 18, 1924 2Sheets-Sheet 1 By Q. B.M

ATTORNEY v 9 2 0 May 1927' P. o. VAN ESSEN EI'AL 6 6651 BREECH MECHANISMFiled July 18, 192 p2 Sheets-Sheet 2 2/ 35,. 40311:"! n J r if, i: 5i i/""-.;j---- a; 4/ 29 X Patented May 3, 1927.

s'r'rs PIETER DANIEL VAN.ESSE1\T, 0F HAAG, NETHERLANDS, AND CLARENCEHERVY FROELICH, OF BETHLEHEM, PENNSYLVANIA.

BBEECH MECHANISM.

Application filed July 18, 1924. Serial No. 726,659.

Our invention relates to the construction of a breech mechanism for agun, and is more particularly intended for use in smooth bore guns andtrench mortars adapted to fire projectiles of rearwardly tapering or ofstream line form that leave a substantial amount of free space betweentheir walls and the bore of the gun, as for example, projectiles ot thetype mentioned in a co-pending application for a; patent by PieterDaniel Van Essen, Serial No. 713,513, filed May 15, 19%.

Smooth bore guns, such as trench mortars or infantry howitzers, areintended to fire a comparatively heavy projectile at low muzzlevelocities, conditions in which it is difficult to obtain constantballistics. For this reason, quickburning powders are preterred, buttheir use has hitherto necessitated the reinforcement of the gun almostto its muzzle in order to Withstand the high pressures generatedtherein. This results in an appreciable increase in the weight of thegun and impairs its mobility.

The use of trench mortars by lnfantry from a covered position requiresthat their position shall not be disclosed to the enemy. The muzzleflame or flash at the discharge of the projectile from a gun enables theenemy to locate its position, andthis is more especially so during anight attack. This flash is caused by the self ignition of combustiblebut unconsumed gases when they come into contact with the air, whichsupplies the oxygen for combustion in which the said gases aredeficient. These gases leave the muzzle of the gun at high temperatureand pressure, and at a short distance away from the gun they becomesuificiently mixed withthe surrounding atmosphere to become ignited andproduce a luminous flame of spherical shape which immediately disclosesthe position of the gun. This phenomenon is the more pronounced in thecase of quick burning powders. It has been attempted to overcome this incertain cases by the addition of small quantities of oxygen carryingmaterial to the composition of the propellent powder, with the object ofeilecting a more complete combustion within the bore of the gun and alsoobtaining a more regular burning of the powder. l/Vhile Such additionsdo reduce the muzzle flame, they nevertheless act as smoke producers, sothat when fired in daylight they still disclose the position of the gun.It is, therefore, highly desirable to obviate the muzzle flame by someother means than those referred to.

An object of our invention is to provide a propellent charge chamber fora gun having restricted communication with the latter, whereby pressureswill be better distributed throughout the passage of the projectilethrough the bore of the gun, thereby making it possible to use a lightertube construction, and whereby combustible material and gases are morecompletely consumed thereby avoiding. muzzle flame or an undue amount ofsmoke when firing.

A further object of our invention is to provide an improved type ofbreech block mechanism incorporating a propellent charge chamber havingrestricted communi cation with the interior of a gun tube.

A further object of our invention is to provide a breech blockincorporating a powder chamber open at its rear end and havingrestricted communication with the bore of a gun, together with atransversely mov-- able closure member for the open end of the chamberand carrying a firing device, the closure member in one positionexposing the open end of the powder chamber and in its other positionhaving the firing device over the said chamber.

A further object of our invention is to provide breech mechanismincorporating a block having a bore and an interrupted thread connectionwith respect to a gun and carried by a carrier ring, which is pivotallymounted with respect to the gun tube, together with a closure membertransversely movable with respect to the block and carrying a firingdevice, the transversely movable member in one position exposing thebore of the block and in its other position having the firing devicearranged over the bore.

A further object of our invention is to provide breech mechanism for agun includ ing a block having an interrupted thread connection withrespect to the bore of the gun and being rotatably carried by carrierring lunged at one side of the gun together with means for rotating theblock to release the interrupted thread connection and latch its rearend a carrier ring rotatably supporting the block and hinged laterallywith respect to the gun, a closure member transversely slidable withrespect to the block and in one position exposing the open end of thepropellent charge chamber and in its other position closing suchchamber, together with mechanism for turning theblock and moving theclosure member transversely.

A. further object oi our invention is to I provide a gun incorporating abreech block which includes a propellent charge chamber which has portsfor afi'ording communication between the propellent charge chamber andthe gun tube together with a non-erodible lining which surrounds and isspaced from the outer ends of the ports.

In the drawings accompanying this specification, we show:

In Fig. 1, "a rear end elevation of the breech mechanism;

In Fig. 2, a longitudinal section through the breech'end of the gun withthe swinging breech block in elevation and the sliding block in section;

In Fig. 3 a longitr'idinal section of the swinging breech block in itsclosed position in the gun;

In Fig. 4: a cross. sectional view on line IV-IV of Fig. 2 with thesliding block in section and the rear end of the swinging breech blockand the extractor exposed to view;

In Fig. 5 a detailed view in longitudinal section of the extractormechanism, indicated in Fig. 2 by dotted lines;

. "In Fig. 6 a cross sectional view 'on line VI-VI of Fig. 1; and,

In Fig. 7 a detail section VIIVII of Fig. 4, showing one of the inclinedguides of the rectangular portion of the breech block 'and its relationto the sliding block.

Referring now to the drawings for "a better understanding of ourinvention, in

bracket- 17 and the trunnion .pin '13. The

carrier ring 14. supports the "swinging screwed breech block by therearward E-prolongation of the breech screw-thread 16 and is adaptedto-swing about the trunnion pin 13 by means of the brackets 12. We alsorecess -53.-

show a locking bolt of the conventional type for locking the carrierring and the breech block, said locking bolt "consisting of the bolt 20adaptedto engage with a notch 19 in the breech screw and having at itsoutward end a portion 21 engaging one arm of a bell crank lever 22, thelever being piv- ,oted bythe pin 23 to the carrier ring 14 and havingits other arm engaged by a spring 24. From this, it will be apparentthat the spring 24 tends to -tilt the bell crank lever 22 to urge thebolt 20 inwardly so that it may enter the notch 19 when it comesopposite to the latter.

The contour of the swinging breech block may be such as to conform tovany'type of breech seating in general use, that is to say, it maybecylindrical or ogival. The breech threads may likewise be designed inany suitable manner. In-the drawings, we show a swinging screwedblock'of the conventional cylindrical -type with interrupted threads,but having certain important and novel modifications thereto, which.render it particularly adapted to guns, wherein an even and regularmuzzle velocity is diflicult of attainment. I j

.The main "body of the breech block 15 (Fig. ,3) is bored out to receivea combustion chamber 30, secured to it :by the threaded portion 31 andcentrally disposed in the said bore. The liner 32 ofnon-erodiblematerial fits closely the bore of the breech block and is held inposition by sc'rew threads 33, so as to be easily replaceable. Thethickness of this lineris such as to leave an annular clearance 34;bet-ween the combustion chamberBO and the inner wall of the liner 32.The body of the breech block projects rearwardly of the carrier ring 14,said proijecting portion being of rectangular section. The breech blockis also bored out from this rearward projecting end to form a propellentcharge ,or cartridge case chamber 18. An obtur'ator 60 of the Broadwellring type is 'shownforwardly of the breech block 15.

In Figs. 2 and 3, we show two external guide slots 25 parallel to eachother and cutf-in the rectangular portion of the breech block "in adirection transverse'to the gun The rearward faces 26 of these slotsare, however, inclined transversely of the -aXiso-l*' -thegun, asclearly-shown in Figs. 2 and 7. The rear face 27 of the breech block islikewise faced off at 'the'same angle of -'111Cl1112Ll31011, buta-seat28 whose plane 1s normal to the gnu axis 1s.prov1ded for the headof a cartridge case so as to*hold same centrally along the axis of thegun. The

recess 29 in theseat 28 is adapte'd'to containthe-forked end of anextractor and the breech block isfalsosuitably recessed for thes"w-'inging ofthe extractor pivot in a The combustion chamber 30 is o fhollow construction but closed; forwardly. The chamber walls are'designedto safely withstand the maximum pressures developed by thecombustion of the propellent powder in the powder chamber 18. A numberof radial channels or vents 35, preferably four in number, angularlyequidistant from each other, are provided in the walls of the combustionchamber -30 to communicate the propellent gases from 'saidychamberto theannular clearance'34, which is in open communication with the gun. Theopen end 36 of the combustion chamber-is slightly enlargedso as tocorrespond with the propellent charge chamber 18 and be adaptable to themouth of a cartridge case when such is used. In Figs. 3 and 5, weshow acartridge case 37 in the firing position.

The sliding block 40 occupies a position rea rwardly of the swingingblock15 and is intended to securely close the propellent charge chamber18, when the block is centrally disposed in relation to the swingingblock 15. Thissliding block 1 is ofsubstantially rectangular shape withits upper and lower edges'slightly archedand has a portion 41 cut awayto a radius corresponding with the bore of the powder chamber 18, asshown in Fig. 1. At the lower corner of the sliding block,'on the sideopposite to the trunnion brackets, a depending lug 42 is provided havinga groove or slot 43 adapted toengage with a pin 44'which is fixed to thecarrier ring 14 (see Fig. 6). The sliding block 40 is attached to thebreech' block l5-by means of ribs 45 which engage in the guide slots 25-(Figs. 2, 3, 5 and 7), the rearward faces 46 ofsaid' ribs being inclinedat an angle to correspond with and be in contact with the inclined faces26 of the guide slots. This permits of the movement of the sliding blocktransversely to the gun axis, while also providing a slight rearwardwithdrawal of the sliding block from the face'of the swinging breechblock, the inclined contacting surfaces of the guide slots and the ribsproviding a wedge action. The sliding block also carries rearwardly afiring mechanism 47 of the usual type, such for example, as the Ta'skerfiring mechanism, having a firing lever 48, a suitable aperture 49 beingprovided in the sliding blockface for the protrusion of'the firing pmwhen it is desired to fire the gun. I

The propelling charge can be inserted in bags or." in cartridgecases. Inthe" latter "case it'is necessary to provide a"means for extracting thecartridge'case fromits seating, after same has been,fired. We,therefore,show in Figs. 2, 3,4 and 5', a-suitable InethOd'bf achie ingithis "object. 5 The extractor 5O consistsfofausemi-circular forkedporjtio'n51 adapted to closely fit under and 'aroundf'thefhead of thecartridgecase, {a pivoting portion 52suitably supported in the recess 53of the breech block and a finger portion 54, adapted to engage in theguide slot 55 of the sliding block. This guide slot 55 is positioned toone side of the verticai axis of the gun and is disposed transversely ofthe gun and parallel to the guide slots 25. It extends from a point nearthe outer edge of the sliding block to a point substantially in linewith the cartridge case seating 28 where it terminates in a radial slope56. The spring plunger 57 is disposed angularly to the said slot and isadapted to cause the finger portion 54 of the extractor to over-ride itduring the outward and transverse motions of the sliding block and theguide slot 55. The over-rich ing of the finger 54 by the spring plunger57 effects the displacement of the former about the pivot 52 and resultsin the rearward displacement of the forked portion 51 away from therecess 29 in the swinging breech block. During the movement of thesliding block in the reverse direction, that is, towards the axis of thegun, the face of the finger 54 contacts with the plunger 57 and forcesit out of its protruding position in the slot 55, thereby permittingsaid linger of by means of the lever 58. The sliding block 40, beingattached to the swinging block 15 by the ribs 45 engaged in the gaiclesv 25, is capable of transverse movement relatively to the swingingbreech block while also rotating with it. Its free rotation whileoccupying a constant relative position to the breech block is, however,limited by the confines of the tangential guide slot 43 which engageswith the fixed pin 44 of the carrier ring 14. This results in a combinedangular and transverse displacement of the sliding block 40 in respectto the gun, until the breech block 15 having been rotated through 90degrees, the sliding block 40 occupies a position such as is indicatedin the dotted lines of Fig. 1. In this position the powder chamber 18 isexposed. The'n'iovement of D the opening of the breech of the gun iseffected by swinging the complete mechanism, viz, the carrier ring 14,the swinging breech block 15, the expansion chamber 30, the slidingblock 4-0 and the firing gear e7, away from the confines of the breechring ill, by means of the carrier ring brackets 12 which pivot about thetrunnion pin 13. The breech block 15 is free to rotate in the carrierring 14: from the engaged to the disengaged positions of itsinterruptedthreads, owing to the small notch 19 inthe breech block whichduring rotation to the disengaged position is moved into alignment withthe locking bolt 20, so that said locking bolt being actuated by the camlever 22 and the compression spring 24 engages with this notch as soonas the breech threads are fully disengaged, and in this manner locks thebreech block to the carrier ring and permits the block to be swung outor swung back to its seating by the lever 58 without loss of its properposition in respect of its interrupted threads.

After the cartridge case is inserted in the powder chamber 18, thebreech block 15 is caused to reengage with the breech ring threads bythe reversed rotation .of the breech block and the lever 58. During thisrotation, a transverse movement of the sliding block 4:0 is againeffected, by the engage ment of the slot 4.3 with the fixed pin let,said movement being, however, in a. direction opposite to that alreadydescribed, in other words, the 'powder chamber 18 is gradually closed bythe interception of the sliding block 40 and the firing pm of the liringgear 4? is brought to a position coincident with the axis of the gun andthe center oi the cartridge case in the powder chamber 18, and ready toimpact with the firin cap of the cartridge primer upon release or thefiring lever 48-.

Owing to the use of a substantially closed combustion chamber, the gaspressure developed by the firing of the powder in the cartridge case isrestrained from immediate expansion into the free space in the gun, andan average pressure can be maintained in the gun by means of thedistributing channels 35 and the annular clearance 36. This restraintproduces a building up 01" pressure in the combustion chamber over andabove the pressures developed by the normal burning of the propellentpowder. The building up of this pressure also increases the rate ofburning of the powder witlrthe result that a high local pressureis'rapidly accumulated in the explosion chamber, which is designed so asto be fully capable of withstanding'this high pressure. The restrictedoutlets 35 serve to distribute this pressure evenly to the bore of thegun during the whole of the travel of the pro p p p I p H r I I ignitionof, a propellent powder" d'lspdsed jecti'le along the bore, with theresult that a moderate; average pressure is maintained in thegunhuntilthe projectile hasbeen discharged. r, Furthermore, the use ofa. special combustionchamber permits; of a substantially completecombustion of they propellent powder in the chamber itself so. that onlynoncombustible and permanent gases are passed to the bore of the gun.Even it" some small amount of combustible gas does pass to the gun,the;loss of temperature due to its'expansion. results in the coolingofsaid. gases below their incandescent state. Hence no muzzle'fl'ame willbe produced. The gases enter theboreof the gun at high temperature and,high velocity and for this reason, We provide the liner 32 of erosionresisting steel, where erosion is likely to take place.

We do not limit our invention tothe particular design and the method ofconstruction we have here described, as it is evidently susceptible ofvarious modifications, apparent to anyone skilled in the art, withoutdeparting from the spirit of our invention. Weintend thatonly suchlimitations shal11be-placed thereupon as arelimposed by the; prior artor as are; specifically set forth in-theappended claims- Havingthusdescribed our invention what we claim as new and desire to secure byLetters Patent is: 1. In a gun, the combination; of a member havingapro'pellent powder chamber therein, said chamber being of substantiallysmaller diameter than the bore .of the gun, whereby an" annularclearance may be provided between the chamber and the gun whenthe formeris within the confines of the latter,- and a pivotal connection betweenthe, tube and the member.

2. In a gumthe combination of a member having a propellent powderchamber therein, means for pivotally connecting the member and: the?gun,,: and pressure. distributing meansfor applying asubstantiallyconstant average pressure tothe bore ofv the gun during; the;eombustioni of the propell-ent charge and untilthe projectile has been.discharged from the. gun.

. In a gun, the combination of a member having asubstantially closed:powder chamber therein,.means for pivotally connectingthe member and thegun, and a pressure throttling meansin the powder chamber directlycommunicating with thebore of,thegun, for-regulating the admission ofthe powder pressure thereto on the firing of the; propellent. .charge;

4-. In a gun, the. combination of a member. havin a,subs tantiallyclosed powder chamber is erein, restricted-outlets" in the powder.chamber: directly; communicating with thebore of. the g stodelaythfeeapansionaof the combustion gases due to the within thechamber, and means for pivotally connecting the member to the gun so asto intercept the bore of the gun in one position of said member, whilepermitting the insertion of a projectile in the gun bore, in the otherposition of the member.

5. The combination, with a gun, of a pressure accumulator adapted tocommunicate with the bore, means for pivotally connecting theaccumulator to the gun, said accumulator adapted to store permanentgases at high temperatures and high pressures resulting from thecombustion of a propellent powder charge, and means to apply said gasesto the gun at substantially reduced temperatures and pressures.

16. The combination, with a gun having a breech block receiving portionaxially aligned therewith, of a breech block for said portion having apropellent charge chamber closed at its forward end and open at itsrearward end, said block having means for afi'ording restricted lateralcommunication between the chamber andthe interior of the gun.

7. In a gun, the combination of a gun tube, a member adapted tofit inthe breech end of the tube and having a powder chamber adapted tocontaina charge of propellent powder, the bore of the tube being adaptedto contain a projectile forwardly of the member, and the member havinganintercepting wall between said powder chamber and the tube and said wallbeing provided with small perforations to oppose entry into the bore ofunconsumed combustible gases capable of causing muzzle flame.

8. In a gun, the combination of a tube having an axial bore for aprojectile, a breech mechanism for the tube, said mechanism including apowder-chamber-defining member adapted to project within the bore of thegun when the breech is closed and being of smaller diameter than thebore of the tube so as to provide an annular clearance for the passageof gun gases about the periphery of the member, the member being adaptedto be withdrawn from the confines of the tube, andineans to efiectseating and ithdrawal of said member.

9. In a gun, the combination of a gun tube, a breech block for the guntube and provided with a rearwardly-open powder chamber, a member foropening and closing the powder chamber, and a firing device carried bythe member, said block having restricted passages to affordcommunication between the powder'chamber and the bore of the tube toprovide for even distribution of gas pressure to the latter.

10. In a breech mechanism for a gun, the combination of a rotatablescrewed closure member intercepting the bore of the gun and having arearwardly open powder chamber, a transversely slidable closure memberintercepting the open end of the powder chamber, a firing device carriedby the slidable closure member, said first closure member havingrestricted passages to afford communication between the powder chamberand the bore of the gun for the even distribution of gas pressure to thelatter, means to impart rotation to the screwed closure member torelease the latter from the gun, means dependent upon angular movementof the screwed closure member for imparting transverse movement of thesecond closure member, and means providing for the withdrawal of thefirst closure member from its intercepting position after apredetermined angular movement thereof.

11. In a breech mechanism for a gun, the combination of a rotatablescrewed closure 'member adapted to intercept the bore of the municationbetween the powder chamber and the bore of the gun, means to effect thewithdrawal of the closure members from their respective interceptingpos1t1ons,and

an extractor to withdraw a cartridge case from the powder chamberactuated by the slidable closure member when it moves relatively to thescrewed closure member.

12 In a gun, the combination of a. breech closure member having a powderchamber provided with restricted outlet means, a

closure member'forthe powder chamber, a firing device carr1ed by thepowder chamber closure member, and mechanism for moving both closuremembers to open and closed positions. 7

13. In a gun, closure member having a propellent powder chamber withrestricted outlet means and adapted to receive a cartridge casecontaining the propellent charge, a closure member for the powderchamber, a firing device carried by the powder chamber closure member,mechanism for moving both closure members to open and closed positions,and e):- tracting' means to withdraw the cartridge case fromfthe powderchamber, said eX- tracting means being actuated by the movement ofoneclosure member relatively to the other closure member during a phase,-

of the opening movement of theVfirst-named member. v

14. The combination with a gun, of a breech block provided with apropellent charge chamber and having an interrupted thread connectionwith respect to the gun, a carrier. ring for the block, a pivotalconnection between the gun and the carrier ring, a closure membermovable transversely of the block and in oneposition exposing the prothecombination of a breech lit) pellent charge chamber for loading, andmeans dependent upon rotary movement of the block and of the member forsliding the lattertransversely.

15. In a breech mechanism for a gun, the combination of a main rotatableportion adapted to close the breech and bored to receive a powdercharge, a transversely slidable portion rearwardly attached to the mainrotatable portion, said slidable portion having a guide slot therein,and a fixed pin attached to the gun and adapted to engage the guideslot, whereby rotation of the main portion effects the movement of theslidable portion in a relatively transverse direction.'

' 16. In a breech mechanism for a gun, the combination of a mainrotatable portion adapted to close the breech and bored to receive apowder charge, a slidable portion carried by the main rotatable portion,a guide slot disposed in the slidable portion, a fixed pin attached tothe gun and adapted to engage the guide slot, whereby rotation of themain portion effects the movement of the slidable portion in arelatively transverse direction, a lever for effecting said ro tation ofthe main portion, a cartridge ejector operable by the transversemovement of the sliding block, and a firing device attached to thesliding block.

17. In a gun, the combinationof a breech ring provided with threads, aswinging breech block having threadsfor engagement with the ring threadsand provided with a rearwardly opening combustion chamber for thepropellent charge, means to effect the withdrawal of the screwed breechblock from the confines of the breech ring, a sliding block disposedrearwardly of the breech block to close the explosion chamber, means toeffect the movement of the sliding block transversely to the axis of thegun, and guide means for confining said transverse movement to theclosing and opening of the combustion chamber.

18. In a gun, the combination of a breech ring having interruptedinternal threads, a breech block having interrupted external threads forengagement and disengagement with the threads of the breech ring, acarrier for supporting the breech block, said breech block having apropel-lent charge chamber open at its rear end, means for effecting theengagement and disengagement of the threads, means for interlocking thecarrier and the breech block after such disengagement has been effectedto prevent relative rotary movement therebetween, means providing formovement of the carrier toinsert and to remove the breech block from theconfines of the gun, a sliding block closure to intercept the open endof the chamber,

an interlocking guide connection between the closure and the breechblock and disposed transversely thereof, means responsive to rotarymovement'of the breech block to effect transverse movement of theclosure, at firing device attached to the closure, and means forthrottling the passage of gases from the chamber to the bore of the gun.

19. In a gun, the combination of a breech ring having interruptedinternal threads, a breech block having interrupted external threads forengagement and disengagement block, a sliding block closure for thepowder chamber, an interlocking guide connection between the closure andthe block and disposed transversely of the latter, means responsive torotary movement of the block 'to impart transverse movement to theclosure, a firing'devlce attached to the sliding" closure, means forthrottling the passage of propellent gases from the combustion chamberto the bore of the gun, and means for ejecting a cartridge case from.the chamber dependent upon transverse opening move- 'ment of theclosure.

20. The combination of a gun and breech mechanism, the gun beingarranged to receive a projectile forwardly of the breech mechanism andthe breech mechanism being adapted to receive a cartridge casecontaining propellent powder, the breech mechanism including a majorbreechclosure memher having a chamber for a cartridge case and a septumWall for separating the chamber from the projectile, a minor breechclosure for opening and closing the cartridge case chamber, said minorclosure having a guide slot, a fixed extracting lever pivotally attachedto the major closure, the lever having a forked member to engage acartridge case and a finger member to engage the guide slot in the minorclosure, and a spring plunger radially inclined to the axis of the gunand disposed in the minor closure so as to intercept the guide slot,whereby the out ward transverse movement of the minor closure relativelyto the major closure causes the finger member of the extractor tooverride the spring plunger and effect the rearward displacement of theforked member, whereas the inward transverse movement of the minorbreech closure causes the finger member to compress the spring plungerfrom its intercepting position, without effecting the displacement ofthe forked member.

21; In a breech loading gun having a prope-llent powder chamber memberindependent of the guntube', the combination of a forward breechclosure, a rearward breech closure, means to move the latter to openandto close said powder chamber, and means to move the former to openand to close the gun bore. a

22. In a breech loadinggun having apropellent powder chamber memberindependent of the gun tube, the combination of a main breech closurerearwardly closing the bore of the gun, a closure rearwardly closing thepowder chamber, and mechanism for opening and closing both closures.

23. In a breech loading gun having a propellent powder chamber memberindepende-nt of the guntube, the combination of a main breech closurerearwardly closing the bore of the gun, a closure rearwardly closingsaid powder chamber, means for moving the main breech closure, and meansdependent upon movement of the main breech closure for moving the powderchamber closure.

24. In a breech block for a gun, the combination of an outer memberhaving a .passage extending therethrough, said passage having portionsof small and large diameter and a portion of small diameter beingadapted to receive a cartridge case, an inner shell member having achamber open at one end and having its open end secured to the outermember with the chamber thereof aligned with the cartridge case portionof the pas sage of the outer member, the inner member being smaller thanthe portion of the passage of the outer member of larger diameter,whereby a space is provided between the inner and the outer members, andthe inner member being provided with ports extending through the wallthereof for affording communication between its chamber and the spacebetween the inner and the outer members.

25. In a breech block mechanism, the combination of a member having anaxial .passage consisting of three portions of successively largerdiameters, the first portion being adapted to receive a cartridge case,a hollow member open at one end and arranged within the portions of thefirst member of intermediate and largest diameters and having its openend secured in the pas sage of the first member of intermediatediameter, said second member having radial ports for affordingcommunication between the chamber thereof and the space between thefirst member and the hollow member.

26. In a breech block mechanism for a gun, the combination of a firstblock member having an axial passage consisting of three portions ofsuccessively larger diameters and the first portion being adapted toreceive a cartridge case, a second member having a chamber and open atone end, the open end being connected to the portion of the passage ofthe firstmember of intermediate diameter, the second member beingprovided wlth ports for affording communication between the chamberthereofandthe space between the first and the second members, and aprotective lining for the portion of the passageway of the first memberof largest diameter.

. 27. In a breech block mechanism for a gun, the combination of innerand outer block members which together define a propellent chargechamber closed at its forward end, the inner and the outermembers beingspaced ap'artfrom the forward ends thereof rearwardly and the innermember being pro-- vided with lateral ports to afford restrictedcommunication bet-ween the propellent charge chamber and the spacebetween the members, and a substantially non-e-rodible lining for theouter member in the space between the inner and the outer members.

28. The combination with a gun having a breech block receiving chamberprovided with interrupted threads, a breech block having interruptedthreads to be engaged and disengaged with respect to the threads of saidchamber, a carrier ring for the breech block, a pivotal connectionbetween the carrier ring and the gun, means for turning the block toengage and disengage the interrupted threads, said block having arearwardly openingpropellent charge chamber, a member carried by andslidable transversely of the block to cover and uncover the chamber, andmechanism arranged between the carrier ring and the transversely movablemember for imparting transverse movement to the latter member when theblock is turned,

29, The combination with a gun having a breech block receiving chamberprovided with interior interrupted threads, of a block havinginterrupted threads to fit the interrupted threads of. said chamber, acarrier ring having threads to fit threads on the block, a pivotalconnection between the carrier ring and the gun, means for turning theblock withrespect to the carrier ring to engage and disengage theinterrupted threads; said block being provided with a propellent chargechamber opening rearwardly, a member carried by and movable transverselywith respect to the block for covering and uncovering said chamber,firing mechanism carried by said member and arranged to be over thechamber when the member covers the latter, and a cam connection betweensaid member and the carrier ring whereby upon turning of the block andof said member the latteris caused to move transversely to cover oruncover the propellent charge chamber.

30. The combination with a gun having a breech block receiving chamberprovided with interior interrupted threads, a breech block havingexternal threads with the forward portions thereof interrupted to fitthe interrupted threads of the chamber, a carrier ring having threads tofit the rearward threads of the block, a pivotal connection 'between thecarrier ring and the gun, means for turning the block with respect tothe carrier ring to engage and disengage the interrupted threads, saidblock having a propellent charge chamber opening rearwardly, atransversely movable member having a guide connection with respect tothe block for covering and uncovering the propellent charge chamber,mechanism arranged between the carrier ring and said member, wherebyupon turning of the block and of said member, the latter is caused tomove transversely to cover and uncover the propellent charge chamber, anejector carried by the block and having a portion to eject a cartridgecase from the chamber, and means carried by the transversely movablemember for operating the ejector upon movement of the transverselymovable member in a direction to expose the propellent charge chamber.

31. The combination with a gun having a breech block receiving chamberprovided with interior interrupted threads, a breech block havingforward interrupted threads to fit the interrupted threads of thechamber and rearward threads, a carrier ring having interior threadsfitting the rearward threads,

a pivotal connection between the carrier ring and the gun, means forturning the block with respect to the ring to engage or disengage theinterrupted threads, latch mechanism carried by the ring for holding theblock in a fixed position with respect to the ring when the interruptedthreads are dis engaged, said block having a rearwardly open propellentcharge chamber, a member carried by and movable transversely withrespect to the block to cover and uncover the chamber, firing mechanismcarried by said member and arranged to be over the chamber when themember covers the latter, cam mechanism arranged between thetransversely movable member and the ring for imparting transversemovement to said member upon rotary movement of the block and of saidmember, an ejector carried by the block and having a portion to engage acartridge case inserted in the chamber, and means carried by thetransversely movable member for actuating the ejector when said memberis moved in a direction to uncover the propellent charge chamber.

32. The combination with-a gun having a breech block receiving portion,of a breech block for said portion having a propellent charge chamberclosed at its forward end and open at its rearward end, said blockhaving means for affording restricted lateral communication between thechamber and the interior of the gun.

33. The combination'with a gun, of a breech block adapted to fit withinthe breech end of the gun and having an explosion chamber, means forinserting and withdrawing the breech block, and means for atfordingrestricted communication between said chamber and the .bore of the gun.

34- In a gun, the combination of a gun tube, a member having anexpansion chamber therein, said member being rearwardly disposed in thegun, a block member insertable and removable with respect to the tubeand defining a powder chamber, means to fire the powder in the powderchamber, means to connect the block to the expansion chamber member soas to communicate the gases of combustion to the latter, and means forconducting the expanded. gases to the gun tube at an averagepressure'during the combustion of the powder.-

35. In a gun, the combination of a gun tube, a member having.anexpansion chamber therein, said member being rearwardly disposed inthe gun, a gas generator memher for propellent gases in directcommunication with the expansion chamber and pivotally connected to thegun, means to effect said communication, and means for conducting theexpanded gases to the gun tube at an average pressure until thedischarge of a projectile from the gun tube.

36. In a gun, the combination with a gun tube, of a breech block for thetube, said block having an expansion chamber for gases resulting fromthe combustion of a propellent charge, and means affording restrictedcommunication between the chainber and the tube.

In testimony whereof I hereunto afiix my signature this 7th day of July,1924.

PIETER DANIEL VAN ESSEN. In testimony whereof I hereunto affix mysignature this 16th dayof July, 1924.

CLARENCE HERVY FROELICH.

